Merge pull request #777 from geocoder-php/patch-2

Adding `"prefer-stable": true` on all composer.json

Author: Nyholm

composer.json

@@ -39,6 +39,7 @@
         "test-ci": "vendor/bin/phpunit --coverage-text --coverage-clover=build/coverage.xml"
     },
     "minimum-stability": "dev",
+    "prefer-stable": true,
     "extra": {
         "branch-alias": {
             "dev-master": "4.0-dev"